JP2020068313A - Light emitting element and manufacturing method of display device - Google Patents

Abstract

To provide a manufacturing method of a display device, which can surely transfer a light emitting element at a desired position of a circuit board, and further has a high yield.SOLUTION: A manufacturing method of a display device, comprises: a step of flattening by coating a flatness film 4 onto a growing substrate 1 in which a light emitting element main body having an electrode pad is integrally formed; a step of exposing the electrode pad by removing the flatness film on the electrode pad; a step of forming an external electrode pad 5 connected to the electrode pad onto the flatness film; a step of arranging the growing substrate to a circuit board 7 in which a circuit side electrode part 8 is formed so that the external side electrode pad is opposite to the circuit side electrode part, to electrically connect the external electrode pad and the circuit side electrode part; and a step of peeling-off the growing substrate from the light emitting element main body and the flatness film.SELECTED DRAWING: Figure 15

Description

  The present invention relates to a method for manufacturing a light emitting device and a display device.

  Micro LED displays have been attracting attention as next-generation display devices. A micro LED display is a display device in which fine light emitting diode (hereinafter referred to as LED) chips as light emitting elements are densely spread over the surface of a display substrate. In the manufacture of such a micro LED display, it is important to accurately and surely arrange the micro LED chips on the surface of the display substrate.

  In Patent Document 1, chips obtained by dividing a wafer are sequentially attached on a support substrate so as to be arranged at a predetermined pitch, and after sealing the chips with a sealing resin layer, the support substrate is peeled off to produce a pseudo wafer. A method is disclosed. In this method, an electrode, an insulating film, and the like are further formed on the pseudo wafer, and then the pseudo wafer is cut by a scribe line to produce, for example, a chip component such as a light emitting element. Patent Document 1 discloses a technique for handling this chip component, transporting it to a predetermined position on a wiring board, and mounting it using solder bumps.

JP, 2004-363279, A

  In the method of manufacturing the above chip component, a step of disposing a large number of individual chips on a separately prepared supporting substrate at a predetermined position, a step of peeling the supporting substrate to produce a pseudo wafer, an electrode on the pseudo wafer Many processes are required, such as a process of manufacturing a dummy wafer, a process of cutting a pseudo wafer with a scribe line, and dividing into many chip parts.

  In order to manufacture a display device using the above chip components, each chip component is transferred onto a circuit board by handling and then mounted using solder bumps or the like. In this manufacturing method, it takes a long time to mount all the chip components. In the above method, it is difficult to realize highly accurate bonding in a process involving heating of solder bumps or the like due to factors such as material deformation and elongation.

  Further, as a method of transferring the chip component to the circuit board, there is a method of transferring using a film or the like. This method includes a step of transferring a chip part to a film and a step of transferring the chip part transferred to the film to a substrate. This method has a problem that the number of transfer steps increases, and the possibility of positional deviation increases due to an increase in the positioning accuracy of the bonding apparatus and the number of transfers. Even if any of the above-mentioned methods is used, there is a problem that the manufacturing yield of the display device is lowered. Particularly, in order to mount a fine micro LED chip on a circuit board to manufacture a display device, a method of mounting the micro LED chip efficiently and without causing a positional shift is desired.

  The present invention has been made in view of the above problems, and the present invention provides a method for manufacturing a display device capable of reliably transferring a light emitting element to a desired position on a circuit board and having a high yield. To aim. Another object of the present invention is to provide a light emitting element that can be reliably transferred to a desired position on a circuit board.

  In order to solve the above-mentioned problems and achieve the object, a first aspect of the present invention is a method for manufacturing a display device, which comprises a growth substrate on which a light-emitting element body including an electrode pad is integrally formed. A step of applying a flattening film to perform flattening, a step of removing the flattening film on the electrode pad to expose the electrode pad, and an outer electrode pad connected to the electrode pad. The step of forming on the flattening film, and disposing the growth substrate on the circuit substrate on which the circuit-side electrode portion is formed so that the outer electrode pad faces the circuit-side electrode portion. The method further includes the step of electrically connecting the outer electrode pad and the circuit-side electrode portion, and the step of peeling the growth substrate from the light emitting element body and the planarization film.

  In the first aspect, it is preferable that the area occupied by the outer electrode pad is set to be larger than the area occupied by the electrode pad.

  In the first aspect, in the step of peeling the growth substrate, laser lift-off is performed in which the interface between the growth substrate and the light emitting element body and the planarization film is irradiated with laser from the growth substrate side. It is preferred to carry out the method.

  In the first aspect, the flattening film is preferably made of a photosensitive resin.

  In the first aspect, a plurality of the light emitting element bodies are formed on the growth substrate, and the outer electrode pads are formed on the flattening film, and then the light emitting element bodies adjacent to each other are formed. It is preferable that the flattening film is processed so as to be separated, and the light emitting element body and the flattening film surrounding the light emitting element body are divided into islands on the growth substrate.

  In the first aspect, in the step of selectively connecting the outer electrode pad of the light-emitting element body to the circuit-side electrode portion of the circuit board and peeling the growth substrate, It is preferable that the substrate is peeled off only from the light emitting element body having the outer electrode pad connected to the circuit side electrode portion and the flattening film surrounding the light emitting element body.

  A second aspect of the present invention is a light emitting device, which comprises at least one of a growth substrate, a light emitting device body including an electrode pad formed on the growth substrate and formed on an upper surface, and the electrode pad. A flattening film that covers the light emitting element body so as to be buried so that the portion is exposed; and an outer electrode pad that is disposed on the flattening film and is electrically connected to the electrode pad. preferable.

  In the second aspect, it is preferable that the area occupied by the outer electrode pad is set larger than the area occupied by the electrode pad.

  In a second aspect, a pair of the electrode pads is formed on an upper surface of the light emitting element body, the outer electrode pad is connected to each of the pair of electrode pads, and each of the pair of electrode pads is connected to the outer electrode pad. It is preferable that the pair of outer electrode pads are formed so as to extend in a direction in which they are separated from the electrode pads connected to each other.

  In the second aspect, it is preferable that the growth substrate is a growth sapphire wafer, and the light emitting element body is a micro LED bare chip integrally provided on the growth substrate.

  According to the present invention, a light emitting element can be reliably transferred to a desired position on a circuit board, and a method for manufacturing a display device with high yield can be realized. Further, according to the present invention, it is possible to realize a light emitting element that can be reliably transferred to a desired position on a circuit board.

FIG. 1 is an explanatory plan view showing a state in which micro LED bare chips are formed on a growth sapphire wafer used in the method for manufacturing a display device according to the first embodiment of the present invention. FIG. 2 is a sectional view taken along the line II-II of FIG. FIG. 3 is a cross sectional view taken along the line III-III of FIG. FIG. 4 is a cross-sectional explanatory view showing a state in which a planarizing film is applied on a growth sapphire wafer so that the micro LED bare chip is buried in the method for manufacturing a display device according to the first embodiment of the present invention. 1 shows a state cut along the same plane as the II-II cross section of FIG. FIG. 5 is a cross-sectional explanatory view showing a state in which a planarizing film is applied on a growth sapphire wafer so that the micro LED bare chip is buried in the method for manufacturing a display device according to the first embodiment of the present invention. 1 shows a state of cutting along the same plane as the III-III cross section of FIG. FIG. 6 is an explanatory plan view showing a state in which the window of the electrode pad of the micro LED bare chip has been opened in the method for manufacturing the display device according to the first embodiment of the present invention. FIG. 7 is a cross-sectional explanatory view showing a state where the electrode pad of the micro LED bare chip is opened in the method for manufacturing the display device according to the first embodiment of the present invention, and is a cross section taken along line II-II of FIG. 1. It shows the state cut at the same plane. FIG. 8 is a cross-sectional explanatory view showing a state in which the electrode pad of the micro LED bare chip has been opened in the method for manufacturing the display device according to the first embodiment of the present invention, and is a cross section taken along line III-III of FIG. 1. It shows the state cut at the same plane. FIG. 9 is a plan explanatory view showing a state in which the enlarged electrode pad is formed on the flattening film in the method for manufacturing the display device according to the first embodiment of the present invention. FIG. 10 is a cross-sectional view taken along line XX of FIG. 11 is a cross-sectional view taken along the line XI-XI of FIG. FIG. 12 is a plan view of a circuit board including a circuit-side electrode portion used in the method for manufacturing the display device according to the first embodiment of the present invention. FIG. 13 is a cross-sectional view taken along line XIII-XIII of FIG. FIG. 14 is a view showing the method of manufacturing the display device according to the first embodiment of the present invention, in which the enlarged electrode pad formed on the growth sapphire wafer side and the circuit side electrode portion on the circuit board side are anisotropically conductive. FIG. 2 is a cross-sectional explanatory view showing a state in which the films are connected and bonded to each other, and a state cut along the same plane as the II-II cross section in FIG. 1 is shown. FIG. 15 is a cross-sectional explanatory view showing a laser lift-off process in the method for manufacturing the display device according to the first embodiment of the present invention, and shows a state cut along the same plane as the II-II cross section of FIG. 1. FIG. 16 is a cross-sectional explanatory view of the display device completed by peeling the growth sapphire wafer in the method for manufacturing the display device according to the first embodiment of the present invention. FIG. 17 is a cross-sectional explanatory diagram of a display device in which the enlarged electrode pad and the circuit-side electrode portion are connected by using solder, showing a modified example of the method for manufacturing the display device according to the first embodiment of the present invention. . FIG. 18 shows a structure in which a circuit pattern including an insulating layer and a contact hole is formed on a micro LED and a glass substrate to be bonded in the method for manufacturing a display device according to the second embodiment of the present invention. FIG. FIG. 19 is a cross-sectional explanatory view showing a laser lift-off step of peeling a growth sapphire wafer in the method for manufacturing a display device according to the second embodiment of the present invention. FIG. 20 is a cross-sectional explanatory view of the display device completed by peeling off the growth sapphire wafer in the display device manufacturing method according to the second embodiment of the present invention. FIG. 21 shows that in the method for manufacturing a display device according to the third embodiment of the present invention, a growth sapphire wafer on which micro LEDs are formed is subjected to patterning including an exposure step to form island-shaped micro LED chips in a matrix. It is a plane explanatory view showing the state formed in a shape. 22 is a cross-sectional explanatory view showing a state of being cut along the lateral direction in FIG. 21 so as to pass through the electrode pad on the cathode side and the enlarged electrode pad. 23 is a cross-sectional explanatory view showing a state of being cut along the vertical direction in FIG. 21 so as to pass through both the anode side and the cathode side electrode pads. FIG. 24 is a cross-sectional view showing a state in which the micro LED chip formed on the growth sapphire wafer side is selectively soldered to the circuit board in the method for manufacturing a display device according to the third embodiment of the present invention. FIG. FIG. 25 is a cross-sectional explanatory view showing a state in which laser lift-off is performed on the interface between the selectively connected micro LED chip and the growth sapphire wafer in the method for manufacturing a display device according to the third embodiment of the present invention. Is. FIG. 26 is a cross-sectional explanatory view showing a display device completed by peeling the sapphire wafer from the selectively connected micro LED chips in the method for manufacturing a display device according to the third embodiment of the present invention.

  Hereinafter, a method of manufacturing a display device according to an embodiment of the present invention and details of a light emitting element will be described with reference to the drawings. However, it should be noted that the drawings are schematic and that dimensions, ratios of dimensions, shapes, and the like of each member are different from actual ones. In addition, the drawings include portions having different dimensional relationships, ratios, and shapes.

[First Embodiment]
The method of manufacturing the display device according to the first embodiment of the present invention will be described below with reference to FIGS. The light emitting device according to the present invention can also be manufactured by the method for manufacturing a display device according to the present embodiment. In the present embodiment, a micro LED display is applied as the display device. In this embodiment, a growth sapphire wafer is used as the growth substrate, but various growths such as a silicon carbide (SiC) substrate and a gallium nitride (GaN) substrate are performed depending on the desired emission color, type of light emitting element, and the like. Of course, it is also possible to apply a substrate for use.

(Growth substrate)
First, a growth sapphire wafer 1 including a micro LED chip 30A as shown in FIGS. 1 to 3 is prepared. FIG. 1 shows a partial region of the growth sapphire wafer 1. This growth sapphire wafer 1 is integrally formed on the surface (growth surface) so that island-shaped micro LED bare chips 30A as a light emitting element body form a matrix. The micro LED bare chip 30A is not an individual chip. Here, it is referred to as a micro LED bare chip 30A in order to distinguish it from the micro LED 30 configured to be covered with the flattening film 4 described later.

  The growth sapphire wafer 1 including such a micro LED bare chip 30A is manufactured by a known method using a crystal growth technique, an electrode formation technique, an element isolation technique, or the like.

  The micro LED bare chip 30A includes a semiconductor layer 2 formed by stacking a plurality of semiconductor thin films formed on a growth sapphire wafer 1. An electrode pad 3A as an anode and an electrode pad 3C as a cathode are formed on the upper surface of the semiconductor layer 2. In addition, as shown in FIGS. 1 to 3, in the present embodiment, the pair of electrode pads 3A and 3C provided on the micro LED bare chip 30A are formed at the same height position. It may be formed on the upper surface of a different height.

  The semiconductor layer 2 has a structure in which gallium nitride-based semiconductor thin film layers are laminated, and for example, on the growth sapphire wafer 1, an AlGaN film, a GaN film, an InGaN / GaN film (quantum well), and a GaN film are sequentially formed. A structure in which, for example, are laminated can be given.

  As shown in FIG. 1, in the present embodiment, the electrode pads 3A and 3C formed on the semiconductor layer 2 are spaced apart from one end side and the other end side in the longitudinal direction of the semiconductor layer 2.

(Step of flattening)
Next, as shown in FIGS. 4 and 5, the flattening film 4 is applied onto the growth sapphire wafer 1. In this embodiment, a UV-curable photosensitive adhesive is used as the flattening film 4. As shown in FIGS. 4 and 5, the flattening film is applied so that the electrode pads 3A and 3C are buried.

(Step of exposing the electrode pad)
6 to 8 show a state in which the electrode pads 3A and 3C in the present embodiment are exposed. In the present embodiment, UV light irradiation is performed on regions other than the electrode pads 3A and 3C, and the flattening film 4 on the electrode pads 3A and 3C that is not cured is removed to expose the electrode pads 3A and 3C from the flattening film 4. I am letting you. In the area where the electrode pads 3A and 3C are exposed, all of the electrode pads 3A and 3C may be exposed, or some areas of the electrode pads 3A and 3C may be exposed.

(Step of forming outer electrode pad)
As shown in FIGS. 6 to 8, with the electrode pads 3A and 3C exposed from the flattening film 4, a metal such as copper (Cu) or silver (Au) is flattened by the sputtering method. Is deposited on the entire surface of. Thereafter, the well-known photolithography method and etching method are used to form enlarged electrode pads 5 and 6 as outer electrode pads having a shape as shown in FIG. The area occupied by the enlarged electrode pads 5 and 6 is set larger than the area occupied by the electrode pads 3A and 3C. In this way, as shown in FIGS. 9 to 11, a plurality of micro LEDs 30 are formed side by side.

  As shown in FIG. 9 and FIG. 11, in the present embodiment, the enlarged electrode pads 5 and 6 extend so as to be longer in the direction away from the electrode pads 3A and 3C connected thereto, respectively, and have a wide width. It is formed in a shape.

(Circuit board)
12 and 13 show the circuit board 7 used in the present embodiment. A drive circuit (not shown) is formed on the circuit board 7 and is used as a display board. Circuit-side electrode portions 8 and 9 are formed on the circuit board 7 at positions corresponding to the enlarged electrode pads 5 and 6. The circuit-side electrode portions 8 and 9 are arranged on the circuit board 7 at positions corresponding to the pixel regions in which the light emitting element portions (micro LEDs) are mounted. Since the enlarged electrode pads 5 and 6 extend in the direction in which they are separated from each other, as shown in FIG. 12, the circuit-side electrode portions 8 and 9 can be arranged at positions separated from each other on the circuit board 7.

(Connection process)
Next, as shown in FIG. 14, with respect to the circuit board 7, the growth sapphire wafer 1, the enlarged electrode pads 5 and 6, and the circuit-side electrode portions 8 and 9 and the anisotropic conductive film 10 to which they correspond, respectively. Place them so as to face each other. Thermocompression bonding (hot pressing) is performed under appropriate pressure and temperature conditions. As a result, the corresponding enlarged electrode pads 5 and 6 and the circuit-side electrode portions 8 and 9 are electrically connected to each other.

(Peeling process for growth substrate)
Next, the growth sapphire wafer 1 is separated from the micro LED bare chip 30A and the planarization film 4 by using the laser lift-off method. Specifically, as shown in FIG. 15, laser light L is irradiated from the growth sapphire wafer 1 side toward the interface between the growth sapphire wafer 1 and the semiconductor layer 2 and the flattening film 4. . As the laser light, for example, a wavelength of a picosecond laser: a fourth harmonic (FHG) is applied. Since many crystal defects exist in the GaN layer near the interface, almost all of the laser light absorbed here is converted into heat. As a result, ablation occurs at the interface between the growth sapphire wafer 1 and the flattening film 4, and the growth sapphire wafer 1 can be easily peeled off. At the interface between the growth sapphire wafer 1 and the semiconductor layer 2, gallium nitride (GaN) is decomposed into Ga and N ₂ by heat, and the growth sapphire wafer 1 can be peeled off.

(Display device)
FIG. 16 shows a display device 50 completed by peeling off the growth sapphire wafer 1. The display device 50 has a structure in which the semiconductor layers 2 are arranged in an exposed state on the surface opposite to the circuit board 7.

  In the method of manufacturing a display device according to the present embodiment, the enlarged electrode pads 5 and 6 formed on the flattening film 4 on the growth sapphire wafer 1 side are attached to the circuit side electrode portions 8 and 9 of the circuit board 7. To match. The enlarged electrode pads 5 and 6 formed on the flattening film 4 are integrally provided on the growth sapphire wafer 1 side. Therefore, as shown in FIG. 14, when the growth sapphire wafer 1 side and the circuit board 7 side are bonded together, the semiconductor layers 2 to be pixel regions and the enlarged electrode pads 5 and 6 may be displaced. Can be prevented. Therefore, according to the present embodiment, it is possible to accurately transfer the light emitting element body including the micro LED bare chips 30A to the circuit side electrode portions 8 and 9 on the circuit board 7 side at desired positions.

  In the present embodiment, the flattening film 4 is used to make the surface facing the circuit board 7 flat, and the enlarged electrode pads 5 and 6 as outer electrode pads are formed on this flat surface. Therefore, in the present embodiment, all of the enlarged electrode pads 5 and 6 on the growth sapphire wafer 1 side can be arranged in the same plane. Therefore, when the growth sapphire wafer 1 side and the circuit board 7 side are bonded together, it is possible to prevent a gap from being generated between the enlarged electrode pads 5 and 6 and the circuit side electrode portions 8 and 9, and ensure a reliable connection. Can be done.

  Further, in the present embodiment, since the enlarged electrode pads 5 and 6 as the outer electrode pads are formed on the flat surface of the flattening film 4, the area occupied by the enlarged electrode pads 5 and 6 is smaller than that of the electrode pads 3A and 3C. It can be made larger than the occupied area. In the present embodiment, the enlarged electrode pads 5, 6 are made larger than the area occupied by the electrode pads 3A, 3C, so that the contact resistance with the circuit side electrode portions 8, 9 can be reduced. Further, by making the enlarged electrode pads 5, 6 larger than the occupied areas of the electrode pads 3A, 3C, the positioning accuracy is relaxed when the enlarged electrode pads 5, 6 and the circuit side electrode portions 8, 9 are connected. be able to.

  Furthermore, by making the enlarged electrode pads 5 and 6 larger than the occupying areas of the electrode pads 3A and 3C, the connection using the anisotropic conductive film 10 or solder can be performed as in the present embodiment. The display device 51 shown in FIG. 17 is a modification in which the enlarged electrode pads 5 and 6 and the circuit-side electrode portions 8 and 9 are connected by solder 11 and adhered by an adhesive layer 12. According to the present embodiment, since it is possible to use the anisotropic conductive film 10 and solder even in the manufacturing process of a high-definition display device having micro LEDs as pixels, the existing connection device can be used, Manufacturing equipment becomes inexpensive.

  In the present embodiment, by using the photosensitive adhesive as the flattening film 4, there is an effect that it is possible to easily open the windows of the electrode pads 3A and 3C and solidify the flattening film 4 by light irradiation. In the present invention, it is possible to use other resin materials or inorganic materials for the flattening film 4.

  In the present embodiment, since the enlarged electrode pads 5 and 6 are formed so as to extend in the direction away from each other, the enlarged electrode pads 5 and 6 are connected to the circuit-side electrode portions 8 and 9 at positions apart from each other, so that miswiring occurs. Can be suppressed.

[Second Embodiment]
18 to 20 show a method of manufacturing a display device according to the second embodiment of the present invention. In the constituent members used in the present embodiment, the same members as the constituent members in the first embodiment described above are designated by the same reference numerals, and detailed description thereof will be omitted.

  As shown in FIG. 18, in the present embodiment, the insulating layer 13 is formed after the semiconductor layer 2, the electrode pads 3A and 3C, the flattening film 4, and the enlarged electrode pads 5 and 6 are formed on the growth sapphire wafer 1. The contact hole 14, the circuit pattern 15, the insulating layer 16, the contact hole 17, the circuit pattern 18, and the insulating layer 19 are sequentially formed. The structure above the enlarged electrode pads 5 and 6 constitutes a pixel lighting pattern or circuit. Next, as shown in FIG. 18, a glass substrate 20 as a supporting substrate is attached onto the uppermost insulating layer 19. A substrate made of a material other than glass may be used as the supporting substrate.

  Next, the growth sapphire wafer 1 is separated by using the same laser lift-off method as in the first embodiment, and the display device 52 as shown in FIG. 20 is completed.

[Third Embodiment]
21 to 26 show a method of manufacturing a display device according to the third embodiment of the present invention. In the constituent materials used in the present embodiment, the same members as the constituent members in the first embodiment described above are designated by the same reference numerals, and detailed description thereof will be omitted.

  First, as shown in FIG. 21, in the present embodiment, micro LED chips 31 as a plurality of light emitting elements are formed on a growth sapphire wafer 1 so as to be arranged at a predetermined pitch. As shown in FIG. 23, the micro LED chip 31 includes a growth sapphire wafer 1, a semiconductor layer 2, electrode pads 3A and 3C, and enlarged electrode pads 5 and 6.

  As shown in FIG. 23, the planarization film 4 between the semiconductor layers (included in the light emitting element body) 2 adjacent to each other is processed so as to be separated. As a result, the semiconductor layer 2 and the flattening film 4 surrounding the semiconductor layer 2 can be divided into islands on the growth sapphire wafer 1 as shown in FIG.

  Next, a circuit board 7 as shown in FIG. 24 is prepared. In this circuit board 7, the circuit-side electrode portions 8 are arranged at a pitch that is an integral multiple of the pitch of the micro LED chips 31 on the growth sapphire wafer 1. In the present embodiment, the pitch of the circuit-side electrode portions 8 is set to be twice (an integral multiple) the pitch of the micro LED chips 31. As shown in FIG. 24, in the present embodiment, the micro LED chip 31 is selectively connected to the circuit side electrode portion 8. In this embodiment, the surface of the circuit-side electrode portion 8 is plated with solder 11 and is used.

  Next, as shown in FIG. 25, laser light L is applied to only the interface region between the micro LED chip 31 connected to the circuit-side electrode portion 8 and the growth sapphire wafer 1 by using the laser lift-off method.

  Then, as shown in FIG. 26, the growth sapphire wafer 1 surrounds the semiconductor layer (included in the light emitting element body) 2 having the enlarged electrode pad 5 connected to the circuit-side electrode portion 8 and the semiconductor layer 2. It is peeled off only from the flattening film 4. In the present embodiment, it becomes possible to selectively transfer the micro LED chip 31 formed on the growth sapphire wafer 1 to the circuit board 7 side.

[Light emitting element]
Here, prior to the description of the configuration of the micro LED 30 as the light emitting element according to the present embodiment, the problems in the conventional micro LED will be described. The conventional micro LED chip is transferred to the circuit board side by adhesion or soldering using a film or the like. With such a transfer method, it is difficult to accurately align the electrode pads of the micro LED chip with the circuit board side. That is, when a high-definition display device is manufactured using a micro LED chip having a side length of 10 μm or less, the length of the electrode pad in the micro LED chip is 1 of the side length of the micro LED chip. Since it is / 2 or less, it is necessary to bond the circuit side electrode portion provided on the circuit board with an accuracy of ± several μm or less. As described above, in the transfer method using film, adhesion, solder, etc., it was not possible to perform highly accurate bonding due to factors such as positioning accuracy of the bonding device, material deformation due to the heating process at the time of connection, and elongation. . Further, in the micro LED, since the electrodes are minute, it is not possible to use the conventional bonding process using an anisotropic conductive film (ACF) or solder.

  Hereinafter, the configuration of the micro LED 30 as the light emitting device according to one embodiment of the present invention will be described with reference to FIGS. 9 to 11. The same members as the constituent materials in the present embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. In the present embodiment, a plurality of micro LEDs 30 share the same growth sapphire wafer 1, and the individual micro LEDs 30 may be separated by the growth sapphire wafer 1 in an island shape, or The plurality of micro LEDs 30 may not be separated on the growth sapphire wafer 1.

  As shown in FIG. 11, the micro LED 30 according to the present embodiment emits light including the growth sapphire wafer 1 and a pair of electrode pads 3A and 3C formed on the growth sapphire wafer 1 and formed on the upper surface. The semiconductor layer 2 that constitutes the micro LED bare chip as the element body, the flattening film 4 that covers the semiconductor layer 2 so that at least a part of the electrode pads 3A and 3C are exposed, and the flattening film 4 And enlarged electrode pads 5 and 6 as outer electrode pads electrically connected to the electrode pads 3A and 3C. Although the width of the growth sapphire wafer 1 is drawn narrow in the drawings, the growth sapphire wafer 1 is used for growing a semiconductor thin film such as the semiconductor layer 2 and has a desired diameter. Have.

  In this embodiment, the area occupied by the enlarged electrode pads 5 and 6 is set larger than the area occupied by the electrode pads 3A and 3C. As shown in FIG. 11, the pair of enlarged electrode pads 5 and 6 are formed so as to extend in a direction away from the electrode pads 3A and 3C connected to each other.

  In the micro LED 30 according to the present embodiment, the surface facing the circuit board 7 side using the flattening film 4 is a flat surface. In the micro LED 30, since the enlarged electrode pads 5 and 6 are formed on the flat surface, the enlarged electrode pads 5 and 6 on the growth sapphire wafer 1 side can be arranged in the same plane. Therefore, when transferring the micro LED 30 to the circuit board 7 side, it is possible to prevent a gap from being generated between the enlarged electrode pads 5 and 6 and the circuit side electrode portions 8 and 9 on the circuit board 7 side, and ensure a reliable connection. Can be done.

  Further, in the micro LED 30 according to the present embodiment, since the enlarged electrode pads 5 and 6 are formed on the flat surface of the flattening film 4, the area occupied by the enlarged electrode pads 5 and 6 is occupied by the electrode pads 3A and 3C. It can be larger than the area. By making the enlarged electrode pads 5, 6 larger than the area occupied by the electrode pads 3A, 3C, the contact resistance with the circuit-side electrode portions 8, 9 can be reduced. Further, by making the enlarged electrode pads 5 and 6 larger than the occupied areas of the electrode pads 3A and 3C, the positioning accuracy is relaxed when the enlarged electrode pads 5 and 6 and the circuit side electrode portions 8 and 9 are connected. be able to.

  Furthermore, by making the enlarged electrode pads 5 and 6 larger than the occupying areas of the electrode pads 3A and 3C, the connection using the anisotropic conductive film 10 or solder can be performed. In manufacturing the micro LED 30 capable of forming high-definition pixels, it is possible to use the anisotropic conductive film 10 and solder accompanied by heat treatment, so that the existing connection device can be diverted and the manufacturing device becomes inexpensive.

  In the micro LED 30 according to the present embodiment, since the enlarged electrode pads 5 and 6 are formed so as to extend in the direction away from each other, the enlarged electrode pads 5 and 6 are connected to the circuit-side electrode portions 8 and 9 at positions separated from each other. Occurrence of incorrect wiring can be suppressed.

[Other Embodiments]
Although the embodiments have been described above, it should not be understood that the statements and drawings forming part of the disclosure of these embodiments limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  For example, in each of the above-described embodiments, the UV-curable photosensitive adhesive is used as the flattening film 4, but the flattening film 4 is not limited to this, and it is possible to flatten and open the electrode pad window. A resin film or an inorganic material film may be used.

  Further, in each of the above-described embodiments, the growth sapphire wafer 1 is separated by using the laser lift-off method. However, between the growth sapphire wafer 1 and the semiconductor layer 2, boron nitride (having a layered crystal structure) is formed. BN) may be interposed, and it may peel mechanically.

  In the method of manufacturing a display device according to the above-described embodiment, an active matrix substrate having a TFT as a circuit substrate may be used, or a drive circuit substrate having a drive circuit that does not use a TFT may be used depending on the drive system of the display device. .

1 Sapphire wafer for growth (growth substrate)
2 Semiconductor layer 3A Electrode pad (anode)
3C electrode pad (cathode)
4 Flattening film 5, 6 Expanded electrode pad (outer electrode pad)
7 Circuit Board 8, 9 Circuit Side Electrode Section 10 Anisotropic Conductive Film 11 Solder 13 Insulating Layer 14 Contact Hole 15 Circuit Pattern 16 Insulating Layer 17 Contact Hole 18 Circuit Pattern 19 Insulating Layer 20 Glass Substrate (Supporting Substrate)
30 micro LED (light emitting element)
30A Micro LED bare chip (light emitting element body)
31 Micro LED chip (light emitting element)
50,51,52,53 display device

Claims (10)

A step of applying a flattening film on the growth substrate integrally formed with a light emitting element body including an electrode pad to perform flattening;
Removing the planarization film on the electrode pad to expose the electrode pad,
Forming an outer electrode pad connected to the electrode pad on the planarization film,
With respect to the circuit substrate on which the circuit-side electrode portion is formed, the growth substrate is arranged so that the outer electrode pad faces the circuit-side electrode portion, and the outer electrode pad and the circuit-side electrode portion are arranged. The step of electrically connecting,
A step of peeling the growth substrate from the light emitting element body and the planarizing film;
And a method for manufacturing a display device. The method for manufacturing a display device according to claim 1, wherein the area occupied by the outer electrode pad is set to be larger than the area occupied by the electrode pad. The laser lift-off method of irradiating the interface between the growth substrate, and the light emitting element body and the planarization film with laser from the growth substrate side is performed in the step of peeling the growth substrate. Alternatively, the method for manufacturing the display device according to claim 2. The method for manufacturing a display device according to claim 1, wherein the flattening film is made of a photosensitive resin. A plurality of light emitting element bodies are formed on the growth substrate,
After forming the outer electrode pad on the planarization film,
The flattening film between the light emitting element bodies adjacent to each other is processed so as to be separated, and the light emitting element body and the flattening film surrounding the light emitting element body are formed into islands on the growth substrate. The method for manufacturing the display device according to claim 1, wherein the display device is divided. The outer electrode pad of the light emitting element body is selectively connected to the circuit-side electrode portion of the circuit board,
In the step of peeling the growth substrate, the growth substrate is formed from only the light emitting element body having the outer electrode pad connected to the circuit-side electrode portion and the flattening film surrounding the light emitting element body. The method for manufacturing a display device according to claim 5, wherein the display device is peeled off. A growth substrate,
A light emitting device body including an electrode pad formed on the growth substrate and formed on the upper surface,
A planarization film that covers the light emitting device body so that at least a part of the electrode pad is exposed;
An outer electrode pad disposed on the planarization film and electrically connected to the electrode pad,
A light-emitting element including. The light emitting device according to claim 7, wherein an occupied area of the outer electrode pad is set larger than an occupied area of the electrode pad. A pair of the electrode pads are formed on the upper surface of the light emitting device body,
The outer electrode pad is connected to each of the pair of electrode pads,
The pair of outer electrode pads connected to each of the pair of electrode pads are formed so as to extend in a direction away from each other of the electrode pads connected to each other. Light emitting element. The growth substrate is a growth sapphire wafer,
The light emitting device according to any one of claims 7 to 9, wherein the light emitting device body is a micro LED bare chip integrally provided on the growth substrate.

Images